Multiwell analysis plates used in automated analytical equipment, including automated biological assay, are widely used. These plates are standardized for use in various instruments, such as epifluorescence multiwell imaging analysis, protein crystal detection and ELISA (Enzyme-Linked ImmunoSorbent Assay). Typically, plastic 96-well plates, having an 8×12 array of wells, are used; however, 6-, 384- and 1536-well plates, and other array arrangements are also used.
US Patent Application Publication No. 2004/0256963 filed by Afflick et al. published Dec. 23, 2004, is directed to an automated sample analysis system capable of handling a large number of multiwell plates. As shown in FIGS. 6-8 and discussed at paragraphs 51 and 89-99, this system uses a robotically operated plate handler. In particular, as stated at paragraph 93, the plate handler in this system does not grasp and lift the plates.
U.S. Pat. No. 6,496,309 issued to Bliton et al. on Dec. 17, 2002 discloses an automated CCD-based micro-array imaging system, but appears to be silent regarding any sample plate handler, e.g., handlers for the gene chip arrays.
U.S. Pat. No. 5,609,381 issued to Thom et al. on Mar. 11, 1997, U.S. Pat. No. 4,808,898 issued to Pearson on Feb. 28, 1989, U.S. Pat. No. 4,699,414 issued to Jones on Oct. 13, 1987, and U.S. Pat. No. 4,579,380 issued to Zaremsky et al. on Apr. 1, 1986, all exemplify parallel grippers that can be used with transporting robots. However, none of these teach or disclose the parallel gripper structure of the present invention using the stepper motor.
During gripping, the plastic plates can be unnecessarily squeezed by the prior gripping devices, causing the plates to buckle and adversely affecting the contents of the well. This can result in inaccurate analyses. Also, the prior gripping devices can grip the sides of the plates at uneven positions, which can adversely affect the analysis.
It is an object of the present invention to provide a parallel gripper usable with a multi-well plate handling robot to grip a multi-well plate that maintains the plate in a horizontal orientation, avoids disruptive squeezing of the plates during gripping, and minimizes or eliminates sudden movements that can disturb the contents of the plate wells.